1. Field of the Invention
This invention relates to reboring tools useful for removing used or damaged plastic pipe fittings from pipes, or plastic pipe from within the fittings. The present invention is particularly directed towards an arbor, centering guide member and cutting head member for structured specifically for removing a plastic closet flange fitting for a toilet from a plastic waste pipe.
2. Description of the Prior Art
In the plumbing industry, when installing water closets or toilets, a closet flange is affixed at floor level to the drainage pipe below floor level to allow bolt-on attachment and sealing of the toilet to the waste line. Closet flanges basically consist of a short tubular hub for attachment to a waste pipe, and an upper outer extending flange attached to the top end of the hub having bolt apertures therein. Today many closet flanges and drainage waste pipes are manufactured of ABS plastic and are permanently bonded together with adhesives at the construction site. While plastic is less expensive and lighter in wight than metal, it may occasionally becomes irreparably damaged, generally during construction of the building before installaton of the toilets. Since the closet flange is permanently affixed to the drainage pipe, and since the hub of the closet flange is recessed below the concrete slab or wooden flooring of the building, replacement of the damaged closet flange has traditionally included removal of a relatively large portion of the flooring surrounding the flange to allow the flange to be cut off the pipe with a hacksaw. Up to now, no portable equipment of tooling has been available which could efficiently remove by reboring the damaged closet flange, withoug disturbing the flooring, and leave the remaining drainage pipe in suitable condition for refitting with a new closet flange. Conventional twist-type drill bits, augers, spade bits and fly cutters are not suited for reboring a closet flange since they rely on a centering point to engage a solid material to steady and direct the cutting edges.
A past art patent search was conducted at the U.S. Patent Office to examine reboring tools capable of removing installed plastic closet flanges from plastic drainage pipes. Of the past art patents examined, those considered somewhat relevant to our invention are as follows:
R. Bean was issued U.S. Pat. No. 1,460,838, on Jul. 3, 1923, for a refacing tool used to reseat or reface the valve seats of internal combustion engines.
A. G. Tanguay was granted U.S. PAT. No. 1,625,836, on Apr. 26, 1927, for a cutting bit comprised of a concavo-convex disc. This disc alone is incapable of reboring a closet flange without the additional elements of a support shaft and a guide member, neither of which has been mentioned or shown.
A U.S. Pat. No. 4,580,934, was issued to W. W. McCormick, on Apr. 8, 1986, for a hole sizing tool for accurately enlarging the size of a previously drilled hole. The tool includes a mandrel, an annular cutting disc, and an annular pilot member and a shank.
On Sept. 15, 1987, M. Heyworth was granted U.S. Pat. No. 4,693,643, for a plastic pipe planing device. The device includes a cylindrical pilot which supports a number of cutting blades and contains a centrally affixed drive shaft.
Also of interest is our own U.S. patent on a reboring tool, U.S. Pat. No. 4,720,219, issued to S. Masonek and F. Rabo, on Jan. 19, 1988, which includes the use of a circular centering guide disc.
The previously mentioned past art patents generally include pilot or guide discs which are circular in shape and therefore could not be used as a centering guide with plastic closet flanges due to the structure of the interior of the flange. The closet flange essentially has three different internal bore diameters, with the narrowest diameter formed by an inward projecting ridge at the top end of the tubular hub of the flange. In order to position the pilot or centering guides of the past art devices down into the lower, larger diameter bore of the hub of the closet flange, the centering guides would have to first be passed through the smaller diameter cylindrical bore at the top of the hub, which is essentially impossible with a circular or annular member, and have the circular guide disc function as a centering guide in the larger diameter cylindrical bore of the hub of the closet flange. If the circular centering guides were sized sufficiently small enough to pass through the narrow cylindrical bore at the top of the hub, they would be too small for bracing against the interior annular wall of the hub, and would be ineffective as centering guides for a bore tool. Therefore, none of the past art devices can effectively remove damaged closet flange from a connect waste pipe.